Search

Copyright of Bagcilar Medical Bulletin / Bağcılar Tıp Bülteni is the property of Galenos Yayinevi Tic. LTD. STI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose This post‐authorisation safety study estimated the risk of anaphylaxis in patients receiving intravenous (IV) iron in Europe, with interest in iron dextran and iron non‐dextrans. Studies conducted in the United States have reported risk of anaphylaxis to IV iron ranging from 2.0 to 6.8 per 10 000 first treatments. Methods: Cohort study of IV iron new users, captured mostly through pharmacy ambulatory dispensing, from populations covered by health and administrative data sources in five European countries from 1999 to 2017. Anaphylaxis events were identified through an algorithm that used parenteral penicillin as a positive control. Results: A total of 304 210 patients with a first IV iron treatment (6367 iron dextran), among whom 13–16 anaphylaxis cases were identified and reported as a range to comply with data protection regulations. The pooled unadjusted incidence proportion (IP) ranged from 0.4 (95% confidence interval [CI], 0.2–0.9) to 0.5 (95% CI, 0.3–1.0) per 10 000 first treatments. No events were identified at first dextran treatments. There were 231 294 first penicillin treatments with 30 potential cases of anaphylaxis (IP = 1.2; 95% CI, 0.8–1.7 per 10 000 treatments). Conclusion: We found an IP of anaphylaxis from 0.4 to 0.5 per 10 000 first IV iron treatments. The study captured only a fraction of IV iron treatments administered in hospitals, where most first treatments are likely to happen. Due to this limitation, the study could not exclude a differential risk of anaphylaxis between iron dextran and iron non‐dextrans. The IP of anaphylaxis in users of penicillin was consistent with incidences reported in the literature. [ABSTRACT FROM AUTHOR]

In recent years, P2P architecture has been established as a major means for distributed data sharing systems, and has been broadly utilized for P2P file sharing (e.g. music, movies, etc.). For the last few years, the database community has begun to exploit P2P paradigms for database applications and a few prototypes have been proposed for P2P database management systems. In this paper, we provide an overview of different challenging issues for building P2P database management systems by presenting existing research related to P2P database management. [ABSTRACT FROM AUTHOR]

This article reviews current research on the issue of semantic conflict resolution in multidatabase system design. It is observed that in multidatabase systems, semantic conflicts need to be resolved at both schema level and instance level. Based on the literature review, a new taxonomy for differentiating semantic conflicts and a meta-data representation incorporating the taxonomy are proposed. It is argued that the new meta-data representation is effective for summarizing local schemata, and hence it can serve as a common protocol for multidatabase systems that require instance level conflict resolution. [ABSTRACT FROM AUTHOR]

Accurate query cost estimation is crucial to query optimization in a multidatabase system. Several estimation techniques for a static environment have been suggested in the literature. To develop a cost model for a dynamic environment, we recently introduced a multistate query-sampling method. It has been shown that this technique is promising in estimating the cost ofa query run in any given contention state for a dynamic environment. In this paper, we study a new problem on how to estimate the cost of a large query that may experience multiple contention states. Following the discussion of limitations for two simple approaches, i.e., single state analysis and average cost analysis, we propose two novel techniques to tackle this challenge. The first one, called fractional analysis, is suitable for a gradually and smoothly changing environment, while the second one, called the probabilistic approach, is developed for a rapidly and randomly changing environment. The former estimates a query cost by analyzing its fractions, and the latter estimates a query cost based on Markov chain theory. The related issues including cost formula development, error analysis, and comparison among different approaches are discussed. Experiments demonstrate that the proposed techniques are quite promising in solving the new problem. [ABSTRACT FROM AUTHOR]

Seamless access to resources and services provided by distributed, autonomous, and heterogeneous systems is central to many advanced applications. Building an integrated system to provide such uniform access and cooperation among underlying heterogeneous systems is both an increasing necessity and a formidable challenge. An important component of such a complex integrated system is a unified language that serves both as a data definition and as a data manipulation tool. Special requirements are posed in the instance of an integrated system which includes database systems among its components. In this paper, we introduce the necessary constructs that an object-oriented programming language should provide for being adopted as the language of the integrated system in such a setting. We adopt a modular, object-based approach to integration. Each component system that joins the integration provides a set of basic classes and pre-defined basic methods. We show how the class hierarchy of the system can be used to provide a uniform way of mapping database resources to basic classes and associative queries to basic methods. A view mechanism is introduced that supports the integration of the basic classes and provides a means of expressing relationships among them and resolving any potential conflicts. The view mechanism is implemented by extending the standard class constructors of an object-oriented language to support the definition of virtual classes. The language provides workflow constructs for defining the structure of programs and for attaining synchronization among concurrently executing programs. Furthermore, atomicity and concurrency control information is included in the form of consistency assertions as part of the interface of each basic method. [ABSTRACT FROM AUTHOR]

Today, enterprises maintain many, disparate information sources over which complex business procedures and applications are executed. The informal and ad hoc characteristics of these environments make the information in them very prone to inconsistency. Yet, the flexibility of application execution given to different parts of an organization is desirable. This paper describes a new mechanism in which the execution of asynchronous, pre-existing, yet related, applications can be harnessed and concurrently executed with traditional, distributed transactions. The types of inconsistency that can arise as a result of this concurrent execution are categorized and methods to control and remove it are proposed. [ABSTRACT FROM AUTHOR]

To meet users' growing needs for accessing pre-existing heterogeneous databases, a multidatabase system (MDBS) integrating multiple databases has attracted many researchers recently. A key feature of an MDBS is local autonomy. For a query retrieving data from multiple databases, global query optimization should be performed to achieve good system performance. There are a number of new challenges for global query optimization in an MDBS. Among them, a major one is that some local optimization information, such as local cost parameters, may not be available at the global level because of local autonomy. It creates difficulties for finding a good decomposition of a global query during query optimization. To tackle this challenge, a new query sampling method is proposed in this paper. The idea is to group component queries into homogeneous classes, draw a sample of queries from each class, and use observed costs of sample queries to derive a cost formula for each class by multiple regression. The derived formulas can be used to estimate the cost of a query during query optimization. The relevant issues, such as query classification rules, sampling procedures, and cost model development and validation, are explored in this paper. To verify the feasibility of the method, experiments were conducted on three commercial database management systems supported in an MDBS. Experimental results demonstrate that the proposed method is quite promising in estimating local cost parameters in an MDBS. [ABSTRACT FROM AUTHOR]

Global query execution in a multidatabase system can be done parallelly, as all the local databases are independent. In this paper, a cost model that considers parallel execution of subqueries for a global query is developed. In order to obtain maximum parallelism in query execution, it is required to find a query execution plan that is represented in the form of a bushy tree and this query tree should be balanced to the maximal possible extent with respect to execution time. A new bottom up approach called Agglomerative Approach (AA) is proposed to construct balanced bushy trees with respect to execution time. By the deterministic nature of this approach, it generates local optimal solutions. This local minima problem will be severe in the case of graph queries, i.e., queries that are represented with a graph structure. A Simulated annealing Approach (SA) is employed to obtain a (near) optimal solution. These approaches (AA and SA) are suitable for handling on-line and off-line queries respectively. A Hybrid Approach (HA), that is an integration of AA and SA, is proposed to optimize queries for which the estimated time to be spent on optimization is known a priori. Results obtained with AA and SA on both tree and graph structured queries are presented. [ABSTRACT FROM AUTHOR]

With the existence of many autonomous databases widely accessible through computer networks, users will require the capability to jointly manipulate data in different databases. A multidatabase system provides such a capability through a multidatabase manipulation language, such as MSQL. We propose a theoretical foundation for such languages by presenting a multirelational algebra and calculus based on the relational algebra and calculus. The proposal is illustrated by various queries on an example multidatabase. It is shown that properties of the multirelational algebra may be used for optimization and that every multirelational algebra query can be expressed as a multirelational calculus query. The connection between the multirelational languages and MSQL, the multidatabase version of SQL, is also investigated. [ABSTRACT FROM AUTHOR]

A multidatabase system (MDBS) is a facility that allows users access to data located in multiple autonomous database management systems (DBMSs). In such a system, global transactions are executed under the control of the MDBS. Independently, local transactions are executed under the control of the local DBMSs. Each local DBMS integrated by the MDBS may employ a different transaction management scheme. In addition, each local DBMS has complete control over all transactions (global and local) executing at its site, including the ability to abort at any point any of the transactions executing at its site. Typically, no design or internal DBMS structure changes are allowed in order to accommodate the MDBS. Furthermore, the local DBMSs may not be aware of each other and, as a consequence, cannot coordinate their actions. Thus, traditional techniques for ensuring transaction atomicity and consistency in homogeneous distributed database systems may not be appropriate for an MDBS environment. The objective of this article is to provide a brief review of the most current work in the area of multidatabase transaction management. We first define the problem and argue that the multidatabase research will become increasingly important in the coming years. We then outline basic research issues in multidatabase transaction management and review recent results in the area. We conclude with a discussion of open problems and practical implications of this research. [ABSTRACT FROM AUTHOR]